The family of hexahydroxy derivatives of cyclohexane is known as inositols. There exist nine different isomers and one of these, myo-inositol, is of biological importance. Chiro-inositols and scyllo-inositols are also naturally occurring but very little is known about their biological role.
Myo-inositol is an essential nutrient for microorganisms and under special dietary conditions for different animals.
There are some known derivatives of myo-inositol such as phosphates and phospholipids.
Myo-inositol is found in plants primarily as its hexaphosphate ester, i.e. phytic acid.
Different specific isomers of myo-inositol phosphates such as D-myo-inositol1,4,5-trisphosphate has been reported in Biochem. Biophys. Res. Commun. 120.2 (1984) p. 481. This compound is known as an intracelluar calcium mobilizer in mammalian cells. Other specific isomers of myo-inositol trisphosphate have been disclosed in the U.S. Pat. No. 4,797,390. Compounds described in the above mentioned patent are used for example in pharmaceutical preparation.
Despite the ionic structure of the compounds the pharmacological effect of these compounds is very significant also after oral administration. However, in order to improve the penetration through biological membranes different lipophilic derivatives of inositol phosphates have been disclosed in the European Patent Application No. 269105. Examples of these are acyloxyalkylesters of inositol phosphates where the phosphate substituents are further esterified with acyloxyalkyl moities.
In certain biological systems it is desirable that the substituents on the inositol phosphate compounds are removed after the penetration of cellular membranes. For example after oral administration of an inositol phosphate derivative it is in many cases important to design the derivative in such a way that the original compound is formed in the blood stream. After the penetration of cell membranes for example esterified inositol phosphates are degraded enzymatically by different forms of esterases. However, in many cases the degradation process is quite slow and thus the formation of the requested compound is retarded.